The correct answer is:
(c) Newton / meter²
Explanation:
A strain gauge is used to measure the strain, which is defined as the change in length divided by the original length of a material. The unit of strain is dimensionless because it represents a ratio. However, when discussing the output of a strain gauge, we typically talk about the change in resistance (in ohms, Ω) that occurs due to the strain applied to the material.
If the question is asking about the quantity that a strain gauge typically measures or is related to, that would be stress (which is force per unit area). The unit of stress is Newton per meter² (N/m²), also known as a Pascal (Pa). The strain gauge is often used to measure the stress caused by strain, which has units of N/m².
The other options:
- Ω/°C: This refers to the temperature coefficient of resistance, not strain.
- Lux: This is a unit of illuminance, unrelated to strain.
- Volts: A strain gauge can generate a voltage output, but its primary measurement is related to strain or stress, not directly to voltage.